For the supply of fuel to combustion chambers of internal combustion engines, use is preferably made of lift-controlled injectors such as, for example, electromagnetically operated injectors. Normally, such injectors have an electronic controller by means of which, for example, an injection duration, an injection amount and/or a multiple injection can be set. With regard to future prescribed limits for pollutant emissions, controllers of said type should increase combustion efficiency and reduce fuel consumption. In the case of conventional injectors, use is generally made of an actuator which performs a lifting movement for the purposes of opening and closing an injection opening. In particular in the case of electromagnetically operated injectors, such lifting movements of the actuator, that is to say an actuation of an armature, which is coupled to a valve needle, by means of a magnetic field, are restricted during the opening and closing movements by a respective abutment, wherein bouncing against the abutments may occur. Here, in particular in the case of injectors in which the valve needle and the armature are not rigidly connected to one another, an overshooting or over travel of the valve needle may occur, such that a flow rate of the fuel during the injection process is impaired. This is manifested in a so-called S-shaped curve in the fuel flow rate, that is to say in a non-linearity in the flow rate characteristic curve of the injector during the injection process, whereby the efficiency of the combustion is reduced.
A further problem is the bouncing of the armature during the closing of the injector, wherein, when the valve needle reaches the valve seat during the closing process, the armature performs a downward follow-through oscillation and, as it returns into its rest position, the valve needle briefly lifts from its valve seat, which can result in undesired post-injections. The additional fuel supplied by the post-injection may be incompletely burned, whereby the pollutant emissions are increased. In addition, over the long term, fuel consumption is increased. Furthermore, owing to the bounce in the current signal, no clear signal for valve seat detection can be identified.
DE 10 2007 060 396 A1 discloses an injector with a needle which is connected via an elastic web to an armature in order that, via the elastic web, equal and opposite vibration movement between the armature and the needle is made possible. Said equal and opposite vibration movement is intended to reduce the overall bounce during the closing process. The construction of an injector of said type is however relatively complex and is furthermore afflicted with the problem of fatigue of the elastic components, which can result in high maintenance outlay.